here's wall street journal columnist simon constable. >> something has vanished from mainstreet. its trust in wall street. as a result small investors are dumping stocks. in fact, even as the stock market has soared close to record highs, mutual and exchange-traded fund investors, a rough proxy for retail stock buyers, have dumped $138 billion in shares, that's billion with a "b", accorng to datarom the investment company institute. some people will tell you that's because small investors are too emotional and so they make terrible decisions. they were burned by the credit crunch and the popping of the tech bubble and are now are gun shy. in short, the message is, they are stupid because they've missed the recent rally, but maybe they aren't. maybe they are justly shy of shenanigans on wall street. new research shows that one in five chief financial officers of public companies admit to cooking the books. the study comes from professors at emory and duke universities. in a survey they found that about 20% of c.f.o.s used accounting tricks that didn't reflect the companies underly